Surface Diffusion Regulation of NanoZSM-5 for Catalysis Promotion on Methanol-to-propene

Mass transfer on surface of nano-zeolites plays an important impact on their catalytic performance. In this work, we investigated a diffusion-controlled strategy to regulate the interface effect and the dynamic behavior of guest molecules at the interface of nanoZSM-5 via chemical deposition of different silicon (Si) or tungsten (W) species, thereby affecting its performance in methanol to propylene (MTP) reaction. It was verified that only about 1% of sedimentary species form stable surface structures by binding with surface hydroxyl groups and defect hydroxyl groups. Under a pressure of 0.2–5 kPa, Si and W modification respectively increased the surface diffusion efficiency of methanol by 50% and decreased it by 60%, demonstrating the bidirectionality of the control strategy. Meanwhile, acidity and structural characterization confirmed that these properties were not strongly affected. Catalytic results showed that surface diffusion enhancement increased the selectivity of ethylene and propylene, and remained stable within 120 h. Mechanism studies have shown that the dynamics of the accumulated surface species is a key intermediate process that connects surface diffusion and catalytic performance.